1. Field of the Invention
The present invention relates to an electrical rotating machine using permanent magnets and coils.
2. Description of the Related Art
Electrical rotating machines such as generators have a stator comprising a plurality of coils and a rotor comprising a plurality of permanent magnets and are configured such that rotational magnetic fields generated by the rotating permanent magnets crossing the coils, thereby generating electromotive force across the coils.
For example, in International Publication WO/03/098781 pamphlet discloses a magnet field rotation type of electrical rotating machine with permanent magnets in which the ratio of the pole number of its rotor core to the pole number of its stator core is at 10:9 or 8:9. This electrical rotating machine is configured such that three in-phase coils are arranged consecutively. The number of turns of coils is not specified in WO/03/098781 pamphlet. Further, in FIG. 6 of WO/03/098781 pamphlet discloses that magnetic poles are added so that each of adjacent magnetic poles of the stator is made to be opposite a permanent magnet of a different polarity at the same electrical angle, thereby increasing effective magnetic flux.
The technique illustrated in FIG. 6 of WO/03/098781 pamphlet, with allowing an electrical rotating machine to be similar in body size to conventional electrical rotating machines, can suppress the amount of generated electricity in the medium to high rotation speed range, thus decreasing coil temperature and also improve output in the low rotation speed range.
However, because each magnetic pole is arranged to be opposite a permanent magnet at the same electrical angle, mechanical angles between the magnetic poles of the stator are not equal, but of three in-phase magnetic poles consecutively arranged, the left and right magnetic poles are displaced closer to the middle one, and hence there is the problem that it is difficult to wind a coil around the middle magnetic pole.
On the other hand, if intervals between the magnetic poles of the stator are made equal, when the middle one of the in-phase magnetic poles coincides in position with a magnetic pole of the rotor opposite it, the two magnetic poles (adjacent coils) adjacent to the middle one deviate in position from magnetic poles of the rotor opposite them. Hence, linkage flux linking to the adjacent coils becomes less than linkage flux linking to the middle magnetic pole. Meanwhile, there is the problem that, because copper loss is proportionate to the turn numbers of the coils wound around the stator, the copper loss in the adjacent coils also increases due to the adjacent coils while linkage flux increases.